Power amplifier apparatus and DC component removing method

Abstract

A power amplifier apparatus includes a dither superimposing unit superimposing DC dither on a digital signal; a switching signal generating unit converting the digital signal on which the DC dither is superimposed by the dither superimposing unit to a pair of drive pulses on high and low sides having opposite levels; and a cancel signal generating unit generating a cancel signal to cancel a DC component caused by the DC dither by changing a ratio of pulse widths of the drive pulses on the high and low sides generated by the switching signal generating unit.

1. A power amplifier apparatus comprising:
 dither superimposing means for superimposing DC dither on a digital signal; 
 switching signal generating means for converting the digital signal on which the DC dither is superimposed by the dither superimposing means to a pair of drive pulses on high and low sides having opposite levels; and 
 cancel signal generating means for generating a cancel signal to cancel a DC component caused by the DC dither by changing a ratio of pulse widths of the drive pulses on the high and low sides generated by the switching signal generating means, 
 wherein the cancel signal generating means includes delay means for delaying at least one of the pair of drive pulses on the high and low sides by a predetermined amount, and 
 changes the ratio of the pulse widths of the pair of drive pulses by performing a logical operation of a delayed drive pulse generated by the delay means and the drive pulse which is not delayed. 
 
   
   
     2. A power amplifier apparatus comprising:
 dither superimposing means for superimposing DC dither on a digital signal; 
 switching signal generating means for converting the digital signal on which the DC dither is superimposed by the dither superimposing means to a pair of drive pulses on high and low sides having opposite levels; and 
 cancel signal generating means for generating a cancel signal to cancel a DC component caused by the DC dither by changing a ratio of pulse widths of the drive pulses on the high and low sides generated by the switching signal generating means, 
 wherein the cancel signal generating means includes threshold adjusting means for adjusting a threshold for switching the pair of drive pulses on the high and low sides generated by the switching signal generating means, and 
 changes the ratio of the pulse widths of the drive pulses by using the threshold adjusting means. 
 
   
   
     3. A DC component removing method comprising the steps of:
 superimposing DC dither on a digital signal; 
 generating a switching signal by converting the digital signal on which the DC dither is superimposed in the dither superimposing step to a pair of drive pulses on high and low sides having opposite levels; and 
 generating a cancel signal to cancel a DC component caused by the DC dither by changing a ratio of pulse widths of the drive pulses on the high and low sides generated in the switching signal generating step, 
 wherein, in the cancel signal generating step, 
 at least one of the pair of drive pulses on the high and low sides is delayed by a predetermined amount, and 
 the ratio of the pulse widths of the pair of drive pulses is changed by performing a logical operation of a delayed drive pulse and the pair of drive pulse which is not delayed. 
 
   
   
     4. A DC component removing method comprising the steps of:
 superimposing DC dither on a digital signal; 
 generating a switching signal by converting the digital signal on which the DC dither is superimposed in the dither superimposing step to a pair of drive pulses on high and low sides having opposite levels; and 
 generating a cancel signal to cancel a DC component caused by the DC dither by changing a ratio of pulse widths of the drive pulses on the high and low sides generated in the switching signal generating step, 
 wherein the cancel signal generating step includes: 
 adjusting a threshold for switching the pair of drive pulses on the high and low sides generated in the switching signal generating step, and 
 the ratio of the pulse widths of the pair of drive pulses is changed in the threshold adjusting step. 
 
   
   
     5. A power amplifier apparatus comprising:
 a dither superimposer configured to superimpose DC dither on a digital signal; 
 a switching signal generator configured to convert the digital signal on which the DC dither is superimposed by the dither superimposer to a pair of drive pulses on high and low sides having opposite levels; and 
 a cancel signal generator configured to generate a cancel signal to cancel a DC component caused by the DC dither by changing a ratio of pulse widths of the drive pulses on the high and low sides generated by the switching signal generator, 
 wherein the cancel signal generator includes a delay circuit configured to delay at least one of the pair of drive pulses on the high and low sides by a predetermined amount, and changes the ratio of the pulse widths of the pair of drive pulses by performing a logical operation of a delayed drive pulse generated by the delay circuit and the drive pulse which is not delayed. 
 
   
   
     6. A power amplifier apparatus comprising:
 a dither superimposer configured to superimpose DC dither on a digital signal; 
 a switching signal generator configured to convert the digital signal on which the DC dither is superimposed by the dither superimposer to a pair of drive pulses on high and low sides having opposite levels; and 
 a cancel signal generator configured to generate a cancel signal to cancel a DC component caused by the DC dither by changing a ratio of pulse widths of the drive pulses on the high and low sides generated by the switching signal generator, 
 wherein the cancel signal generator includes threshold adjustor configured to adjust a threshold for switching the pair of drive pulses on the high and low sides generated by the switching signal generator, and changes the ratio of the pulse widths of the drive pulses by using the threshold adjustor.